Few industries have changed as dramatically during the past 30 years as much as technology. The period from the early ’80s to today has profoundly changed the way we work, correspond, communicate and live.

In that period, Technology Integration Group, No. 1 on the list, has seen the entire evolution from typewriters to tablet computers. Founded in 1981, TIG is the oldest company on the 2012 San Diego Business Journal’s list of Technology Solutions Providers.

The list is ranked by sales volume in San Diego County.

TIG has prospered through this transformative time and has been in the No. 1 spot on SDBJ’s list for the past six years. TIG reported $341 million in local revenue for 2011, up 8 percent from $316 million in 2010.

“We have completed four key acquisitions in recent months,” said Bruce Geier, CEO in an email. “We’re constantly on the lookout for more areas that complement our core service offerings.”

In addition to the company’s headquarters in San Diego, TIG has 23 branch offices in the U.S. and one in Shanghai, China.

Reflecting on the past 30 years, Geier commented that the company has been able to remain profitable in an industry that has been through many cycles.

“It really is like an investment portfolio,” Geier said. “You have to diversify to achieve balance.”

Geier added that in the beginning, TIG was developing software, and then the market shifted and wanted hardware more than software. When hardware margins fell, having revenue from software services sustained the business.

“Over the years, we’ve developed and offered multitude technologies,” Geier said. “And we’ve continued to evolve and grow because we proactively measure leading technology and hire experts in our field to provide our clients complete solutions.”

Also weathering the turbulent cycles in the technology sector is 22-year-old, No. 2 ranked, Genica Corp., the parent company of the online retailer Geeks.com. Geeks.com specializes in computer-related excess inventory, manufacturer-closeouts, high-demand and unusual computer components and peripherals at highly discounted prices, according to the company’s website.

“That’s always been our strategy and our competitive advantage; factory-new products are highly commoditized and, in some cases, price-controlled, said Chris Herzog, vice president e-commerce development in an email. “Products of this variety (manufacturer closeouts, unusual components and peripherals) are somewhat less so, though more and more as time has gone on.”